The present invention relates to a fine particle layer laminated film which is configured in such a manner that the fine particle layers containing ultra fine particles are laminated and an optical functional material that uses this fine particle layer laminated film, which can be used in a filed of an optical apparatus and an optical communication apparatus or the like.
Conventionally, an optical functional material that is used for an optical apparatus and an optical communication apparatus or the like has been manufactured by the use of a vacuum film formation device and an exposure device. For example, various optical filters or the like are manufactured by a vapor deposition method by the use of not less than two kinds of materials having different indices of refraction. Alternatively, a holographic optical element or the like is manufactured by the use of an accurate interference exposure device. However, according to such a method, the vacuum device is needed, so that this involves a problem in cost. Additionally, to manufacture a large optical apparatus involves a problem such that a large vacuum device is inevitably required.
As a method for solving such a problem, recently, a manufacturing method of an optical functional material applying an alternate adsorption process using an organic polymer molecule and a surface sol-gel process using metal alkoxide has been suggested (Shiratori, Oyo Buturi (Japanese), Vol. 69, p. 553 to 557, 2000). This method is different from a conventional one in that it serves to manufacture an optical functional material in a wet processs. Further, since this method uses adsorption and a surface reaction in a liquid phase, this method comprises a process at a room temperature and a normal pressure. Therefore, this method does not require a vacuum device and it can easily manufacture a large optical functional material, so that this method contributes to solution of the conventional problems. Additionally, according to this method, there is an advantage such that a curved surface and a irregular surface car be evenly formed.
However, as a defect of such a method, it is considered that it takes very long time for forming a film since the layers are repeatedly laminated in a molecular order.
In recent years, an ultra fine particle less than a visible light wavelength attracts attention from the point of controlling an index of refraction of a transparent material. An average particle diameter of the ultra fine particle is sufficiently small, so that there is little scattering of light due to a particle. Therefore, the ultra fine particle has an advantage such that the index of refraction can be controlled without losing transparency. However, according to a conventional method, it is very difficult to fill such an ultra fine particle having a small particle diameter in a thin film in the high density. As a result, it is difficult to develop an optical functional material using such an ultra fine particle effectively.
The present invention has been made taking the foregoing problems into consideration, an object of the present invention is to provide a fine particle layer laminated film, which does not require a vacuum device that has been needed for a vapor deposition method or the like, and is capable of being manufactured at a relatively low cost by enhancing low throughput, namely, a problem in the case of a conventional alternate adsorption process is used, and an optical functional material that uses this fine particle layer laminated film.
In order to attain the above described purpose, the present invention provides a fine particle layer laminated film configured in such a manner that a plurality of fine particle layers containing the fine particles, of which average particle diameters are in the range of 1 nm and 95 nm, are laminated; wherein the fine particles in the fine particle layer laminated film are accreted by polymer molecules; there are air spaces within a film of the fine particle layer laminated film; and a density of the fine particles in the fine particle layer laminated film is in the range of 40% and 80% in percentage by volume.
In this way, the fine particle layer laminated film according to the present invention, the fine particles are filled in the fine particle layer laminated film in the high density. Therefore, it is possible to use a property of the fine particle, for example, an index of refraction or the like. Simultaneously, there is an air space within the film, so that it is possible to realize the film having a low index of refraction, which is cannot be realized by a conventional material in which the fine particles are dispersed in a dielectric material such as a plastic or the like. Further, according to the present invention, since the fine particles are glued by a polymer molecule to be layered, it is possible to laminate fine particle layers configured by the fine particles having different indices of refraction, As a result, it is possible to realize a fine particle layer laminated film having a modulated index of refraction, which can be applied for a reflection reducing film, an optical filter or the like.
According to the present invention, it is preferable that a difference in an index of refraction between a fine particle layer having the lowest index of refraction among the above described plural laminated fine particle layers and a fine a particle layer having the highest index of refraction among them is not less than 0.2 in an arbitrary wavelength in the range of not less than 400 nm and not more than 700 nm. It is because that, for example, in the case that a fine particle layer laminated film comprises a fine particle layer laminated film having a modulated index of refraction as described above, it is preferable to have a difference in the index of refraction as described above for effecting its function.
According to the present invention, it is preferable that an index of refraction of at least one fine particle layer in the fine particle layer laminated film is not more than 1.32. By forming a layer having such an index of refraction, it is possible to make a fine particle layer laminated film into an optical function that has not been obtained conventionally, for example, an optical function having an ultra low reflection.
According to the present invention, the present invention provides an optical functional material having A fine particle layer laminated film according to any one of claims 1 to 4 and a supporting material for supporting this fine particle layer laminated film. There is a case such that above described fine particle layer laminated film has no self supporting property. In such a case, the fine particle layer laminated film is used together with a supporting material as an optical functional material.
As a supporting material in this case, as described in claim 6, the supporting material may comprise a transparent base material, which is arranged on one surface of the fine particle layer laminated film. It is because that, since the fine particle layer laminated film according to the present invention is normally formed on a base material, if this base material comprises a transparent base material, it is possible to use this fine particle layer laminated film as an optical functional material as it is without reference to whether there is a self supporting property in the fine particle layer laminated film.
Alternatively, according to the present invention, the supporting material maybe a transparent sealing material, which seals the fine particle layer laminated film with leaving aside one surface of the fine particle layer laminated film. This invention has an advantage such that, a strength of the fine particle layer laminated film is secured and modification of the fine particle layer laminated film is prevented by sealing the fine particle layer laminated film except for a surface at the base material side as well as the fine particle layer laminated film is transparent, for example, in the case that a strength of the fine particle layer laminated film is very weak and it is improper that the fine particle layer laminated film is modified by moisture or the like, so that this fine particle layer laminated film can be used as an optical functional material as it is.
Further, according to the present invention, it is preferable that the fine particle layer laminated film is formed on the supporting material or in the supporting material in a pattern form. It is because that it becomes possible to use the fine particle layer laminated film for various applications such as a color filter and a lens array or the like by forming the present fine particle layer laminated film in a pattern form.
According to the present invention, the present invention provides a manufacturing method of a fine particle layer laminated film for forming a fine particle layer laminated film on a base material by laminating the fine particle layers containing the fine particles, of which average particle diameters are in the range of 1 nm, and 95 nm, according to an alternate adsorption method. According to the present invention, a fine particle is adsorbed according to an alternate adsorption method, so that it is possible to make respective layers to be adsorbed into a rather thick film. Accordingly, differently from a film which is formed according to a conventional alternate adsorption method, it becomes possible to form a fine particle layer laminated film having a thickness, which is necessary in practice, for rather short time, so that it is possible to reduce a labor hour and manufacturing cost.
In this case, it is preferable that the alternate Adsorption method depends on the electrostatic interaction. If this method comprises a method by the use of electrostatic interaction, it is possible to make this fine particle layer laminated film into one having predetermined adsorption strength. Further, it is also possible to manufacture fine particle layer laminated film by using a commercially available material. Therefore, the present invention has an advantage such that to manufacture fine particle layer laminated film is advantageous in cost.
Furthermore, according to the present invention, the present invention provides a manufacturing method of a fine particle layer laminated film comprising a process of
forming a layer containing polymer molecules having a polyelectrolyte on a base material;
preparing a fine particle dispersed liquid, in which the fine particles, of which average particle diameters are in the range of 1 nm and 95 nm, are dispersed in a solvent capable of swelling the layer containing polymer molecules;
forming a fine particle layer laminated film on a base material by means of repeating a fine particle layer forming process, which is a process to contact the layer containing polymer molecules with the fine particle dispersed liquid, for forming the fine particle layer plural times.
According to this method, it is possible to form a fine particle layer easily by bringing a fine particle dispersion liquid into contact with a layer containing the polymer molecules. Further, it is possible to make respective fine particle layers rather thick. Therefore, it becomes possible to form a fine particle layer laminated film having a thickness, which is necessary in practice, for rather short time.
In this case, it is preferable that the polyelectrolyte is a polyelectrolyte having an electric charge opposite to the electric charge of the fine particles and the polyelectrolyte is a water soluble polyelectrolyte.
It is because that, by making an electric charge of a polyelectrolyte and an electric charge of a fine particle opposite to each other, it becomes possible to strongly incorporate a fine particle in a polyelectrolyte by an electrostatic attraction force in addition to Van der Waals force to be fixed, so that it becomes possible to stably fill the fine particles within a polymer molecule substance in the high density. Alternatively, a water soluble polyelectrolyte is preferable. It is because that there are many cases that a fine particle dispersion liquid containing the useful fine particles comprises a water system colloidal solution and in the case of using such a fine particle dispersion liquid, a water soluble polyelectrolyte is preferable.
In a fine particle layer laminated film according to the present invention, the fine particles in the fine particle layer laminated film are filled in the high density, so that it is possible to obtain a laminated film sufficiently having a property of the fine particle, for example, a property such as a low index of refraction or the like. Therefore, the present invention has an effect such that the fine particle layer laminated film according to the present invention can be preferably used for an application such as an antirelection film or the like.